A One Hundred-Year-Study of Climate Change and the Upper Range of Tree Growth (Terminus arboreus) on MT. Getryggen in the Swedish Scandes – Updated Change in an Historical Perspective | Chapter 2 | Emerging Issues in Environment, Geography and Earth Science Vol. 9

 In the context of global climate change, positional treeline change since the early 20th century and up to 2023 was assessed along two elevational transects on Mt. Getryggen in the southern Swedish Scandes. Baseline data within permanent line transects, initially representing the year 1915, i.e. right at the onset of the present warming phase, were compared to later intermittent records up to 2023. These were complemented by repeat photography of individual trees. Concerned species were the regional treeline dominants; mountain birch (Betula pubescens ssp. czerepanovii), Norway spruce (Picea abies), Scots pine (Pinus sylvestris) and Grey alder (Alnus incana). Treelines of these species responded with different degrees of upshifts, although with substantial inter-site variability, related to topoclimatic conditions. Betula displayed the largest advance, by 215 m over the entire past 100 years. This maximum magnitude of change complies with data from widely different parts of the Swedish Scandes. Such a common performance indicates that regionally recorded summer and winter warming by 1.4 and 1.9°C, respectively, is the ultimate cause. In a long-term historical perspective, recorded by local megafossil tree remnants, most congenial conditions for birch and pine growth at high elevations prevailed around 10 500-9400 cal. yr BP, when the local treeline of Betula and Pinus reached 1355 and 1250 m a.s.l., respectively. The former elevation coincides with the upper limit of Vaccinium myrtillus and the upper range of the low-alpine belt. With the exception of Pinus, recent treeline upshifts were mainly accomplished by phenotypic responses of millennial-old krummholz specimens (environmentally dwarfed modes), prevailing as relicts above the treeline by the early 20th century. Only occasionally, has treeline advance by Betula and Picea originated from seed regeneration during the past century. These circumstances may set the limit for further rapid and extensive advance of the last-mentioned species, where and when the pool of high-altitude old-established krummholz specimens becomes depleted. The prospect of further advance of seed disseminated Pinus, is judged to be higher, according to recent trends.

Author(s) Details:

Leif Kullman,
Department of Ecology and Environmental Science, Umeå University, SE 901 87 Umeå, Sweden.

Lisa Öberg,
Old Tjikko Photo Art & Science, Handöl 544, SE 837 71, Duved, Sweden.

Please see the link here: https://stm.bookpi.org/EIEGES-V9/article/view/13830

Largest Rises of Swedish Treelines, Consistent with Climate Change Since the Early-20th Century| Chapter 2 | Challenging Issues on Environment and Earth Science Vol. 6

 Repeat in situ measurements were taken at 14 places across the Swedish Scandes, spanning 800 kilometres from south to north, to estimate treeline advance during the last 100 years. Mountain birch (Betula pubescens ssp. czerepanovii), Norway spruce (Picea abies), Scots pine (Pinus sylvestris), and rowan were among the threatened species (Sorbus aucuparia). The highest height with trees at least 2 metres tall was considered as treeline. The focus is on sites with the most widespread treeline shifts, according to previous regional surveys, in order to reveal the entire influence and strength of climate change on the treeline area. Local limitations (topoclimate) were reduced as a result. Sorbus, Betula, and Picea The phenotypic height growth increment of old-established krummholz achieved treeline rise, whereas Pinus responded by establishing and growing new specimens. Regardless of species, the largest upshifts were in the order of 200 m. (max. 245 m). In terms of historical treeline movements, the new and higher treelines are similar to those that existed around 7000 years ago. Unlike earlier generalisations, there were no evident distinctions between the southern and northern hemispheres. Scandes. The measured rise appears to be a totally expected reaction, based on a common temperature lapse rate of 0.6°C per 100 m altitude and reported regional and centennial summer warming of 1.7°C. This type of performance suggests that, in circumstances of climate warming, treelines are in balance with climate on a centennial scale at optimal sites.

Author(s) Details

Leif Kullman
Department of Ecology and Environmental Science, Umeå University, SE 901 87 Umeå, Sweden.

View Book :- https://stm.bookpi.org/CIEES-V6/article/view/2828